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Tundrite-(Ce) Na2Ce2TiO2(SiO4)(CO3)2 - - Crystal Data: Triclinic. Point Group: 1 . Crystals prismatic, displaying {100}, {010}, {1 01}, {201} and flattened on {010}, or acicular along [001] to 3 cm; as stellate groups or spherulitic masses. Twinning: On {010}, producing pseudorhombohedra.

Physical Properties: : Perfect on {010}. : Splintery. Tenacity: Brittle. Hardness = ~3 D(meas.) = 3.70-4.12 D(calc.) = 4.19

Optical Properties: Transparent to translucent. Color: Brownish yellow, greenish yellow to bright light green. : Yellowish gray to white. Luster: Vitreous to adamantine. Optical Class: Biaxial (+). α = 1.743 β = 1.80 γ = 1.88 2V(meas.) = 76°-84(5)° Orientation: Z ∧ c = 4°-14°; X = [010]. Pleochroism: Weak; X = pale yellow; Z = greenish yellow. Dispersion: r > v, strong. - Cell Data: Space Group: P1 . a = 7.533(4) b = 13.924(6) c = 5.010(2) α = 99°52(2)´ β = 70°50(3)´ γ = 100°59(2)´ Z = 2

X-ray Powder Pattern: Ilímaussaq intrusion, Greenland. 13.49 (100), 2.505 (100), 3.448 (90), 2.766 (90), 3.535 (80), 6.784 (70), 1.914 (70)

Chemistry: (1) (2) (1) (2) SiO2 10.03 9.32 Nb2O5 3.44 2.31 TiO2 12.20 11.17 Ta2O5 0.07 La2O3 8.57 16.16 CaO 0.75 0.34 Ce2O3 24.38 27.03 Na2O 8.20 9.44 Nd2O3 10.25 6.17 CO3 16.38 13.91 RE2O3 5.80 H2O 0.36 Pr2O3 2.13 Total [100.00] 98.80 Sm2O3 0.39

(1) Ilímaussaq intrusion, Greenland; by electron microprobe, C confirmed by loss on ignition; original analysis given as elements, here recalculated to oxides, corresponding to Na1.58(Ce0.89Nd0.36La0.32RE0.20Ca0.08)Σ=1.85(Ti0.92Nb0.16)Σ=1.08O2.12(SiO4)(CO3)1.64. (2) Mont Saint- Hilaire, Quebec, Canada, average of 20 electron microprobe analyses, H2O and CO2 by TGA, - OH confirmed by IR and structure analysis, corresponding to (Na1.906Ca0.039)Σ=1.945(Ce1.030La0.621 Nd0.229Pr0.081Sm0.014)Σ=1.975(Ti0.875Nb0.109)Σ=0.984O2H0.250(Si0.971O4)(C0.989O3)2.

Occurrence: In pegmatite veins associated with syenites.

Association: , lamprophyllite, , rhabdophane (Mt. Lepkhe-Nelm, Russia); natrolite, , albite, aegirine, fluorite, rinkite, (Ilímaussaq intrusion, Greenland); aegirine, albite, analcime, an -group mineral, catapleiite, a eudialyte-group mineral, gonnardite, mangan-, monazite-(Ce), natrolite, quartz, rhodochrosite, sphalerite, vinogradovite (Mont Saint-Hilaire, Canada).

Distribution: On Mt. Lepkhe-Nelm, Lovozero massif, , Russia. In southern Greenland, from the Ilímaussaq intrusion, at Kringlerne, on the Kangerdluarssuk Plateau, and at Kvanefjeld. From Mont Saint-Hilaire, Quebec, Canada.

Name: After the Lovozero massif (formerly the Lovozero tundra), Kola Peninsula, Russia, where it was discovered, and a suffix for the cerium content.

Type Material: A.E. Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, Russia (72020). Other studied material at Canadian Museum of Nature, Ottawa, Ontario (CMNMC 85806).

References: (1) Semenov, E.I. (1963) Mineralogy of the rare earths. Izdatelstvo Akad. Nauk SSSR, Moscow, 209-210 (in Russian). (2) (1965) Amer. Mineral., 50, 2097-2098 (abs. ref. 1). (3) Grice, J., R. Rowe, G. Poirier, and Q. Wight (2008) Tundrite-(Ce) from Mont Saint-Hilaire, Quebec: Crystal- structure analysis and species characterization. Can. Mineral., 46, 413-422. (4) (2008) Amer.

Mineralogical Society of America Handbook of Mineralogy Revised 4/26/2011 Mineral., 93, 1946 (abs. ref. 3 ). (5) Semenov, E.I., M.E. Kazakova, and R.A. Aleksandrova (1967) The Lovozero minerals - , gerasimovskite, and tundrite - from Ilímaussaq, South Greenland. Medd. Grønland, 181(5), 1-11. (6) (1968) Amer. Mineral., 53, 1780 (abs. ref. 5). (7) Shumyatskaya, N.G., A.A. Voronkov, V.V. Ilyukhin, and N.V. Belov (1976) Tundrite, Na2Ce2TiO2[SiO4](CO3)2 - refinement of the and chemical formula. Kristallografiya (Sov. Phys. Crystal.), 21, 705-715 (in Russian). (8) Moller, S.K. (1982) Tundrite from the Ilímaussaq alkaline intrusion, South Greenland. Neues Jahrb. Mineral., Monatsh., 481-494.

Mineralogical Society of America Handbook of Mineralogy Revised 4/26/2011